index.js

/**
 * @param {string} s
 * @param {number} numRows
 * @return {string}
 */
//Distribution 95.33%,runtime 176ms
var convert = function(s, numRows) {
    var res = "";
    if (numRows === 1) return s;
    for (var i = 0; i < numRows; ++i){
        var j = i;
        while (j < s.length){
            res += s[j];
            if (i !== 0 && i !== numRows - 1 && j + (numRows - i) * 2 - 2 < s.length)
                res += s[j + (numRows - i) * 2 - 2];
            j += (numRows - 1) * 2;
        }
    }
    return res;
};
//Distribution 12.15%,runtime 244ms
var convert = function(s, numRows) {
     var i, j;
     if(numRows === 1){
         return s;
     }
     var count = 0;
     var colDirect = true;
     var row = 0, col = 0;
     var map = [];
     for(i = 0; i < s.length; i++){
         map[i] = [];
     }
     for(i = 0; i < s.length; i++){
         if(colDirect){
             map[row][col] = s[i];
             row++;
             count++;
         }else{
             map[row][col] = s[i];
             row--;
             col++;           
             count++;
         }
         if(colDirect && count === numRows){
             count = 0;
             row -= 2;
             col++; 
             colDirect = false;
         }
         if(!colDirect && count === numRows - 2){
             count = 0;
             colDirect = true;
         }
     }
     var res = "";
     for(i = 0; i < map.length; i++){
         for(j = 0; j < map[i].length; j++){
             if(map[i][j]){
                 res += map[i][j];
             }
         }
     }
     return res;
};